U.S. patent application number 17/308711 was filed with the patent office on 2021-09-02 for variable geometry turbocharger.
This patent application is currently assigned to MITSUBISHI HEAVY INDUSTRIES ENGINE & TURBOCHARGER, LTD.. The applicant listed for this patent is MITSUBISHI HEAVY INDUSTRIES ENGINE & TURBOCHARGER, LTD.. Invention is credited to Yoji AKIYAMA, Takeru CHIBA, Yosuke DAMMOTO, Eigo KATOU, Keigo SAKAMOTO, Nariaki SEIKE, Toyotaka YOSHIDA.
Application Number | 20210270182 17/308711 |
Document ID | / |
Family ID | 1000005594685 |
Filed Date | 2021-09-02 |
United States Patent
Application |
20210270182 |
Kind Code |
A1 |
SAKAMOTO; Keigo ; et
al. |
September 2, 2021 |
VARIABLE GEOMETRY TURBOCHARGER
Abstract
A variable geometry turbocharger (100) includes a bearing
housing (10) including a bearing-housing side support portion (40)
configured to support a radially outer portion (38) of a nozzle
mount (16) from a side opposite to a scroll flow passage (4) in an
axial direction of a turbine rotor (2), and wherein at least one of
the following condition (a) or (b) is satisfied: (a) the
bearing-housing side support portion (40) includes at least one
bearing-housing side recess portion (46) formed so as to be
recessed in the axial direction so as not to be in contact with the
radially outer portion (38); (b) the radially outer portion (38) of
the nozzle mount (16) includes at least one nozzle-mount side
recess portion (62) formed so as to be recessed in the axial
direction so as not to be in contact with the bearing-housing side
support portion (40).
Inventors: |
SAKAMOTO; Keigo; (Tokyo,
JP) ; DAMMOTO; Yosuke; (Tokyo, JP) ; KATOU;
Eigo; (Tokyo, JP) ; AKIYAMA; Yoji; (Tokyo,
JP) ; SEIKE; Nariaki; (Tokyo, JP) ; YOSHIDA;
Toyotaka; (Tokyo, JP) ; CHIBA; Takeru; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MITSUBISHI HEAVY INDUSTRIES ENGINE & TURBOCHARGER,
LTD. |
Sagamihara-shi |
|
JP |
|
|
Assignee: |
MITSUBISHI HEAVY INDUSTRIES ENGINE
& TURBOCHARGER, LTD.
Sagamihara-shi
JP
|
Family ID: |
1000005594685 |
Appl. No.: |
17/308711 |
Filed: |
May 5, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16087907 |
Sep 24, 2018 |
11028767 |
|
|
PCT/JP2016/059938 |
Mar 28, 2016 |
|
|
|
17308711 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02B 39/00 20130101;
F02B 37/22 20130101; F04D 27/002 20130101; F02B 37/186 20130101;
F01D 25/243 20130101; F02B 37/24 20130101; F01D 25/145 20130101;
F01D 17/165 20130101 |
International
Class: |
F02B 37/24 20060101
F02B037/24; F02B 39/00 20060101 F02B039/00; F04D 27/00 20060101
F04D027/00 |
Claims
1. A variable geometry turbocharger, comprising: a turbine rotor; a
turbine housing which accommodates the turbine rotor and which
forms at least a part of a scroll flow passage through which
exhaust gas to be supplied to the turbine rotor flows: a bearing
housing accommodating a bearing which rotatably supports the
turbine rotor, the bearing housing being coupled to the turbine
housing; and a variable nozzle mechanism for adjusting a flow of
exhaust gas to the turbine rotor from the scroll flow passage
formed on a radially outer side of the turbine rotor, wherein the
variable nozzle mechanism includes: a nozzle vane disposed in an
exhaust gas flow passage for guiding the exhaust gas from the
scroll flow passage to the turbine rotor; a nozzle mount having an
annular shape and supporting the nozzle vane rotatably, the nozzle
mount forming a flow passage wall on a bearing-housing side of the
exhaust gas flow passage; and a nozzle plate having an annular
shape and being disposed so as to face the nozzle mount, the nozzle
plate forming a flow passage wall on a side opposite to the bearing
housing, of the exhaust gas flow passage, wherein the bearing
housing includes a bearing-housing side support portion configured
to support a radially outer portion of the nozzle mount from a side
opposite to the scroll flow passage in an axial direction of the
turbine rotor, wherein the turbine housing includes a
turbine-housing side support portion configured to support the
radially outer portion of the nozzle mount from a side opposite to
the bearing-housing side support portion in the axial direction,
wherein the nozzle mount is nipped by the turbine-housing side
support portion and the bearing-housing side support portion, and
wherein the turbine-housing side support portion is disposed so as
to protrude toward an inner side of the bearing-housing side
support portion in a radial direction of the turbine rotor, along a
surface of the nozzle mount.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Divisional of U.S. application Ser.
No. 16/087,907, filed on Sep. 24, 2018, which is the National Phase
of PCT International Application No. PCT/JP2016/059938, filed on
Mar. 28, 2016, all of which are hereby expressly incorporated by
reference into the present application.
TECHNICAL FIELD
[0002] The present disclosure relates to a variable geometry
turbocharger.
BACKGROUND ART
[0003] A variable geometry turbocharger adjusts the flow of exhaust
gas to a turbine rotor from a scroll flow passage inside a turbine
housing to change the flow velocity and the pressure of exhaust gas
to turbine blades, so as to enhance the supercharging effect.
[0004] As shown in FIG. 13, a variable nozzle mechanism 012
normally includes a nozzle vane 014 disposed in an exhaust gas flow
passage 026 for guiding exhaust gas from a scroll flow passage 004
to a turbine rotor 002, a nozzle mount 016 having an annular shape
and forming a flow passage wall 028 on the side of a bearing
housing 010, of the exhaust gas flow passage, the nozzle mount 016
supporting the nozzle vane rotatably, and a nozzle plate 018
disposed so as to face the nozzle mount, the nozzle plate 018
having an annular shape and forming a flow passage wall 032
opposite to the bearing housing, of the exhaust gas flow
passage.
[0005] In the variable geometry turbocharger disclosed in Patent
Document 1, the bearing housing includes a bearing-housing side
support portion which supports the radially outer portion of the
nozzle mount from the opposite side to the scroll flow passage in
the axial direction of the turbine rotor, and the turbine housing
includes a turbine-housing side support portion which supports the
radially outer portion of the nozzle mount from the opposite side
to the bearing-housing side support portion in the axial direction.
The nozzle mount is nipped by the turbine-housing side support
portion and the bearing-housing side support portion.
CITATION LIST
Patent Literature
[0006] Patent Document 1: JP2013-72404A
SUMMARY
Problems to be Solved
[0007] According to findings of the present inventors, in a case
where the bearing housing includes the bearing-housing side support
portion supporting the radially outer portion of the nozzle mount
like the variable geometry turbocharger disclosed in Patent
Document 1, as indicated by the arrow H in FIG. 13, the radially
outer portion 038 of the nozzle mount 016 heated by the exhaust gas
flow from the scroll flow passage 004 releases heat toward the
bearing-housing side support portion 040, and heat loss occurs. The
bearing housing is cooled by lubricant oil supplied to the bearing
and has a lower temperature than the nozzle mount. Thus, a great
heat loss tends to occur due to the above heat release.
[0008] When heat loss occurs, the turbine thermal efficiency
decreases, and the performance of the variable geometry
turbocharger also decreases.
[0009] Further, when heat loss occurs, the exhaust gas temperature
of the turbine outlet decreases. Thus, in a case where a catalyst
for purifying exhaust gas is disposed on the downstream side of the
turbine, the temperature of the catalyst decreases and the
performance of the catalyst deteriorates, causing contamination of
exhaust gas with impurity substances (e.g. NOx and SOx).
[0010] The present invention was made in view of the above
described typical problem, and an object is to provide a variable
geometry turbocharger capable of reducing heat loss due to heat
release from the radially outer portion of the nozzle mount to the
bearing-housing side support portion.
Solution to the Problems
[0011] (1) According to at least one embodiment of the present
invention, a variable geometry turbocharger includes: a turbine
rotor: a turbine housing which accommodates the turbine rotor and
which forms a scroll flow passage on a radially outer side of the
turbine rotor: a bearing housing accommodating a bearing which
rotatably supports the turbine rotor, the bearing housing being
coupled to the turbine housing: and a variable nozzle mechanism for
adjusting a flow of exhaust gas to the turbine rotor from the
scroll flow passage. The variable nozzle mechanism includes: a
nozzle vane disposed in an exhaust gas flow passage for guiding the
exhaust gas from the scroll flow passage to the turbine rotor; a
nozzle mount having an annular shape and supporting the nozzle vane
rotatably, the nozzle mount forming a flow passage wall on a
bearing-housing side of the exhaust gas flow passage; and a nozzle
plate having an annular shape and being disposed so as to face the
nozzle mount, the nozzle plate forming a flow passage wall on a
side opposite to the bearing housing, of the exhaust gas flow
passage. The bearing housing includes a bearing-housing side
support portion configured to support a radially outer portion of
the nozzle mount from a side opposite to the scroll flow passage in
an axial direction of the turbine rotor. At least one of the
following condition (a) or (b) is satisfied: (a) the
bearing-housing side support portion includes at least one
bearing-housing side recess portion formed so as to be recessed
toward a side opposite to the nozzle mount in the axial direction,
(b) the radially outer portion of the nozzle mount includes at
least one nozzle-mount side recess portion formed so as to be
recessed to a side opposite to the bearing housing in the axial
direction.
[0012] According to the above variable geometry turbocharger (1),
if the condition (a) is satisfied, with the bearing-housing side
recess portion, it is possible to reduce the contact area between
the bearing-housing side support portion and the radially outer
portion of the nozzle mount, and to reduce heat release amount from
the radially outer portion of the nozzle mount to the bearing
housing, through the heat insulating effect of the air layer
between the bearing-housing side recess portion and the radially
outer portion of the nozzle mount. Accordingly, it is possible to
reduce heat loss due to heat release from the radially outer
portion of the nozzle mount to the bearing housing, and improve the
turbine efficiency and the performance of the turbocharger.
[0013] Further, it is possible to suppress a decrease in the
exhaust gas temperature of the turbine outlet side. Thus, in a case
where a catalyst for purifying exhaust gas is disposed on the
downstream side of the turbine, it is possible to suppress
performance deterioration of the catalyst due to the temperature
decrease of the catalyst, and reduce content of impurity substances
(e.g. NOx and SOx) in the exhaust gas.
[0014] Furthermore, if the condition (b) is satisfied, with the
nozzle-mount side recess portion, it is possible to reduce the
contact area between the bearing-housing side support portion and
the radially outer portion of the nozzle mount, and to reduce the
heat release amount from the radially outer portion of the nozzle
mount to the bearing housing, through the heat insulating effect of
the air layer inside the nozzle-mount side recess portion.
Accordingly, it is possible to reduce heat loss due to heat release
from the radially outer portion of the nozzle mount to the bearing
housing, and improve the turbine efficiency and the performance of
the turbocharger.
[0015] Further, it is possible to suppress a decrease in the
exhaust gas temperature of the turbine outlet side. Thus, in a case
where a catalyst for purifying exhaust gas is disposed on the
downstream side of the turbine, it is possible to suppress
performance deterioration of the catalyst due to the temperature
decrease of the catalyst, and reduce content of impurity substances
(e.g. NOx and SOx) in the exhaust gas.
[0016] (2) In some embodiments, in the above variable geometry
turbocharger (1), the at least one bearing-housing side recess
portion or the at least one nozzle-mount side recess portion
includes a plurality of bearing-housing side recess portions
disposed at intervals in a circumferential direction of the turbine
rotor or a plurality of nozzle-mount side recess portions disposed
at intervals in the circumferential direction.
[0017] According to the above variable geometry turbocharger (2),
with the plurality of bearing-housing side recess portions or the
plurality of nozzle-mount side recess portions provided at
intervals in the circumferential direction, it is possible to
reduce the contact area between the bearing-housing side support
portion and the radially outer portion of the nozzle mount
effectively, and reduce the heat release amount from the radially
outer portion of the nozzle mount to the bearing housing
effectively, through the heat insulating effect of the air layer
inside the nozzle-mount side recess portions.
[0018] (3) In some embodiments, the above variable geometry
turbocharger (1) or (2) further includes a plurality of bolts
disposed at intervals in a circumferential direction of the turbine
rotor and configured to fasten the turbine housing and the bearing
housing in the axial direction. The bearing-housing side recess
portion or the nozzle-mount side recess portion is formed in an
angular range which does not overlap with a center position of a
bolt adjacent to the bearing-housing side recess portion or the
nozzle-mount side recess portion, of the plurality of bolts, in the
circumferential direction.
[0019] According to the above variable geometry turbocharger (3),
for the bearing-housing side recess portion or the nozzle-mount
side recess portion is formed in an angular range that does not
overlap with the center position of an adjacent bolt in the
circumferential direction, it is possible to reduce heat loss due
to heat release from the radially outer portion of the nozzle mount
to the bearing housing while ensuring a fastening force between the
bearing housing and the turbine housing achieved by the bolt.
[0020] (4) In some embodiments, in the above variable geometry
turbocharger (3), the bearing-housing side recess portion or the
nozzle-mount side recess portion is formed to be 5 degrees or more
apart from the center position of the bolt adjacent to the
bearing-housing side recess portion or the nozzle-mount side recess
portion, of the plurality of bolts, in the circumferential
direction.
[0021] According to the above variable geometry turbocharger (4),
for the bearing-housing side recess portion or the nozzle-mount
side recess portion is formed to be 5 degrees or more apart from
the center position of the bolt, it is possible to reduce heat loss
due to heat release from the radially outer portion of the nozzle
mount to the bearing housing while ensuring a fastening force
between the bearing housing and the turbine housing achieved by the
bolts.
[0022] (5) In some embodiments, in the variable geometry
turbocharger according to any one of the above (1) to (4), the
turbine housing includes a turbine-housing side support portion
configured to support the radially outer portion of the nozzle
mount from a side opposite to the bearing-housing side support
portion in the axial direction. The nozzle mount is nipped by the
turbine-housing side support portion and the bearing-housing side
support portion. The turbine-housing side support portion is
disposed so as to protrude toward an inner side of the
bearing-housing side support portion in a radial direction of the
turbine rotor, along a surface of the nozzle mount.
[0023] Typically, to nip the nozzle mount with a simple structure,
the radially inner end of the turbine-housing side support portion
is positioned on the same position as the radially inner end of the
bearing-housing side support portion with respect to the radial
direction.
[0024] In contrast, according to the above variable geometry
turbocharger (5), the turbine-housing side support portion is
disposed so as to protrude toward the inner side, with respect to
the radial direction, of the bearing-housing side support portion
along the surface of the nozzle mount, and accordingly, the area of
the nozzle mount covered with the turbine-housing side support
portion is larger than that in a typical structure (normal design
range). Thus, it is possible to reduce the area of a portion of the
nozzle mount exposed to a high-temperature exhaust gas flow from
the scroll flow passage to the exhaust gas flow passage (heat
transfer area). Accordingly, the heat absorption amount of the
nozzle mount reduces, and thus an increase in the metal temperature
of the nozzle mount is suppressed. Accordingly, the temperature
difference between the nozzle mount and the bearing housing becomes
small, and thus it is possible to reduce heat loss due to heat
release from the radially outer portion of the nozzle mount to the
bearing housing, and improve the turbine efficiency and the
performance of the turbocharger.
[0025] (6) According to at least one embodiment of the present
invention, a variable geometry turbocharger includes: a turbine
rotor; a turbine housing which accommodates the turbine rotor and
which forms at least a part of a scroll flow passage through which
exhaust gas to be supplied to the turbine rotor flows; a bearing
housing accommodating a bearing which rotatably supports the
turbine rotor, the bearing housing being coupled to the turbine
housing; and a variable nozzle mechanism for adjusting a flow of
exhaust gas to the turbine rotor from the scroll flow passage
formed on a radially outer side of the turbine rotor. The variable
nozzle mechanism includes: a nozzle vane disposed in an exhaust gas
flow passage for guiding the exhaust gas from the scroll flow
passage to the turbine rotor; a nozzle mount having an annular
shape and supporting the nozzle vane rotatably, the nozzle mount
forming a flow passage wall on a bearing-housing side of the
exhaust gas flow passage; and a nozzle plate having an annular
shape and being disposed so as to face the nozzle mount, the nozzle
plate forming a flow passage wall on a side opposite to the bearing
housing, of the exhaust gas flow passage. The bearing housing
includes a bearing-housing side support portion configured to
support a radially outer portion of the nozzle mount from a side
opposite to the scroll flow passage in an axial direction of the
turbine rotor. The turbine housing includes a turbine-housing side
support portion configured to support the radially outer portion of
the nozzle mount from a side opposite to the bearing-housing side
support portion in the axial direction. The nozzle mount is nipped
by the turbine-housing side support portion and the bearing-housing
side support portion. The turbine-housing side support portion is
disposed so as to protrude toward an inner side of the
bearing-housing side support portion in a radial direction of the
turbine rotor, along a surface of the nozzle mount.
[0026] Typically, to nip the nozzle mount with a simple structure,
the radially inner end of the turbine-housing side support portion
is positioned on the same position as the radially inner end of the
bearing-housing side support portion with respect to the radial
direction.
[0027] In contrast, according to the above variable geometry
turbocharger (6), the turbine-housing side support portion is
disposed so as to protrude toward the inner side, with respect to
the radial direction, of the bearing-housing side support portion
along the surface of the nozzle mount, and accordingly, the area of
the nozzle mount covered with the turbine-housing side support
portion is larger than that in a typical structure (normal design
range). Thus, it is possible to reduce the area of a portion of the
nozzle mount exposed to a high-temperature exhaust gas flow from
the scroll flow passage to the exhaust gas flow passage (heat
transfer area). Accordingly, the heat absorption amount of the
nozzle mount reduces, and thus an increase in the metal temperature
of the nozzle mount is suppressed. Accordingly, the temperature
difference between the nozzle mount and the bearing housing becomes
small, and thus it is possible to reduce heat loss due to heat
release from the radially outer portion of the nozzle mount to the
bearing housing, and improve the turbine efficiency and the
performance of the turbocharger.
[0028] Further, it is possible to suppress a decrease in the
exhaust gas temperature of the turbine outlet side. Thus, in a case
where a catalyst for purifying exhaust gas is disposed on the
downstream side of the turbine, it is possible to suppress
performance deterioration of the catalyst due to the temperature
decrease of the catalyst, and reduce content of impurity substances
(e.g. NOx and SOx) in the exhaust gas.
[0029] (7) In some embodiments, in the above variable geometry
turbocharger (5) or (6), the turbine-housing side support portion
includes a contact portion to be in contact with the radially outer
portion of the nozzle mount, and a non-contact portion formed on an
inner side of the contact portion in the radial direction, the
non-contact portion facing the nozzle mount via a gap.
[0030] With the above configuration (7), the turbine-housing side
support portion has the non-contact portion on the inner side of
the contact portion with respect to the radial direction, and thus
it is possible to cover the radially outer portion of the nozzle
mount with the turbine-housing side support portion while
suppressing an increase in the contact area between the
bearing-housing side support portion and the radially outer portion
of the nozzle mount. Accordingly, it is possible to reduce the area
of a portion of the nozzle mount exposed to a high-temperature
exhaust gas flow from the scroll flow passage to the exhaust gas
flow passage (heat transfer area), and suppress an increase in the
heat input amount to the radially outer portion of the nozzle mount
from the turbine-housing side support portion. Accordingly, it is
possible to suppress an increase in the metal temperature of the
nozzle mount effectively, and reduce heat loss due to heat release
from the radially outer portion of the nozzle mount to the bearing
housing effectively.
[0031] (8) In some embodiments, in the variable geometry
turbocharger according to any one of the above (5) to (7), an
expression 0.ltoreq.(r1-r3)/(r2-r3).ltoreq.0.75 is satisfied, where
r1 is a distance between a radially inner end of the
turbine-housing side support portion and a rotational axis of the
turbine rotor, r2 is a distance between a radially outer end of the
nozzle mount and the rotational axis, and r3 is a distance between
a radially outer end of the nozzle plate and the rotational
axis.
[0032] According to the above variable geometry turbocharger (8),
it is possible to suppress an increase in the metal temperature of
the nozzle mount effectively while suppressing interference by the
turbine-housing side support portion to a smooth flow in the
exhaust gas flow passage between the nozzle mount and the nozzle
plate, and reduce heat loss due to heat release from the radially
outer portion of the nozzle mount to the bearing housing
effectively.
[0033] (9) In some embodiments, in the above variable geometry
turbocharger (8), an expression
0.ltoreq.(r1-r3)/(r2-r3).ltoreq.0.30 is satisfied.
[0034] According to the above variable geometry turbocharger (9),
it is possible to suppress an increase in the metal temperature of
the nozzle mount effectively while suppressing interference by the
turbine-bearing side support portion to a smooth flow in the
exhaust gas flow passage between the nozzle mount and the nozzle
plate, and reduce heat loss due to heat release from the radially
outer portion of the nozzle mount to the bearing housing
effectively.
[0035] Further, it is possible to suppress a decrease in the
exhaust gas temperature of the turbine outlet side. Thus, in a case
where a catalyst for purifying exhaust gas is disposed on the
downstream side of the turbine, it is possible to suppress
performance deterioration of the catalyst due to the temperature
decrease of the catalyst, and reduce content of impurity substances
(e.g. NOx and SOx) in the exhaust gas.
[0036] (10) In some embodiments, the variable geometry turbocharger
according to any one of the above (1) to (9) further includes a
heat shield member disposed between the bearing-housing side
support portion and the nozzle mount.
[0037] According to the above variable geometry turbocharger (10),
through the heat shield effect of the heat shield member, it is
possible to reduce the heat release amount from the radially outer
portion of the nozzle mount to the bearing housing. Accordingly, it
is possible to reduce heat loss due to heat release from the
radially outer portion of the nozzle mount to the bearing housing,
and improve the turbine efficiency and the performance of the
turbocharger.
[0038] (11) According to at least one embodiment of the present
invention, a variable geometry turbocharger includes: a turbine
rotor; a turbine housing which accommodates the turbine rotor and
which forms at least a part of a scroll flow passage through which
exhaust gas to be supplied to the turbine rotor flows; a bearing
housing accommodating a bearing which rotatably supports the
turbine rotor, the bearing housing being coupled to the turbine
housing; and a variable nozzle mechanism for adjusting a flow of
exhaust gas to the turbine rotor from the scroll flow passage
formed on a radially outer side of the turbine rotor. The variable
nozzle mechanism includes: a nozzle vane disposed in an exhaust gas
flow passage for guiding the exhaust gas from the scroll flow
passage to the turbine rotor; a nozzle mount having an annular
shape and supporting the nozzle vane rotatably, the nozzle mount
forming a flow passage wall on a bearing-housing side of the
exhaust gas flow passage; and a nozzle plate having an annular
shape and being disposed so as to face the nozzle mount, the nozzle
plate forming a flow passage wall on a side opposite to the bearing
housing, of the exhaust gas flow passage. The bearing housing
includes a bearing-housing side support portion configured to
support a radially outer portion of the nozzle mount from a side
opposite to the scroll flow passage in an axial direction of the
turbine rotor. A heat shield member is disposed between the
bearing-housing side support portion and the nozzle mount.
[0039] According to the above variable geometry turbocharger (11),
through the heat shield effect of the heat shield member, it is
possible to reduce the heat release amount from the radially outer
portion of the nozzle mount to the bearing housing. Accordingly, it
is possible to reduce heat loss due to heat release from the
radially outer portion of the nozzle mount to the bearing housing,
and improve the turbine efficiency and the performance of the
turbocharger.
[0040] Further, it is possible to suppress a decrease in the
exhaust gas temperature of the turbine outlet side. Thus, in a case
where a catalyst for purifying exhaust gas is disposed on the
downstream side of the turbine, it is possible to suppress
performance deterioration of the catalyst due to the temperature
decrease of the catalyst, and reduce content of impurity substances
(e.g. NOx and SOx) in the exhaust gas.
[0041] (12) In some embodiments, in the above variable geometry
turbocharger (10) or (11), the heat shield member has a lower
thermal conductivity than each of a thermal conductivity of the
bearing housing and a thermal conductivity of the nozzle mount.
[0042] According to the above variable geometry turbocharger (12),
it is possible to reduce the heat release amount from the radially
outer portion of the nozzle mount to the bearing housing
effectively.
[0043] (13) In some embodiments, in the variable geometry
turbocharger according to any one of the above (10) to (12), the
heat shield member is formed of austenitic stainless steel or
nickel-based alloy.
[0044] According to the above variable geometry turbocharger (13),
it is possible to reduce the heat release amount from the radially
outer portion of the nozzle mount to the bearing housing
effectively, while ensuring the heat resistance performance of the
heat shield member itself.
[0045] (14) In some embodiments, in the variable geometry
turbocharger according to any one of the above (10) to (13), the
heat shield member includes a ring-shaped heat-shield plate
disposed so that the bearing-housing side support portion and the
nozzle mount do not make contact with each other over an entire
angular range in a circumferential direction of the turbine
rotor.
[0046] According to the above variable geometry turbocharger (14),
it is possible to reduce the heat release amount from the radially
outer portion of the nozzle mount to the bearing housing with a
simple configuration.
[0047] (15) In some embodiments, in the variable geometry
turbocharger according to any one of the above (10) to (13), the
heat shield member includes a coating applied to the radially outer
portion of the bearing-housing side support portion or the nozzle
mount.
[0048] According to the above variable geometry turbocharger (15),
it is possible to reduce the heat release amount from the radially
outer portion of the nozzle mount to the bearing housing with a
simple configuration.
Advantageous Effects
[0049] According to at least one embodiment of the present
invention, provided is a variable geometry turbocharger whereby it
is possible to reduce heat loss due to heat release from the
radially outer portion of the nozzle mount to the bearing-housing
side support portion.
BRIEF DESCRIPTION OF DRAWINGS
[0050] FIG. 1 is a schematic cross-sectional view of a variable
geometry turbocharger 100 according to an embodiment of the present
invention, taken along the rotational axis O of the turbocharger
100.
[0051] FIG. 2 is a schematic enlarged cross-sectional view of a
variable geometry turbocharger 100 (100A) according to an
embodiment.
[0052] FIG. 3 is a perspective view of a bearing housing 10 of the
variable geometry turbocharger 100 (100A) depicted in FIG. 2.
[0053] FIG. 4 is a schematic diagram showing positions of a
bearing-housing side recess portion 46 and a bolt 44 with respect
to the circumferential direction.
[0054] FIG. 5 is a schematic enlarged cross-sectional view of a
variable geometry turbocharger 100 (100B) according to an
embodiment.
[0055] FIG. 6 is a diagram showing a relationship between a
temporal change of the temperature of exhaust gas flowing through
the scroll flow passage 4 (004) and a temporal change of the heat
release amount (passage heat amount) from the radially outer
portion 38 (038) of the nozzle mount (016) to the bearing-housing
side support portion 40 (040), for each of the variable geometry
turbocharger 200 according to a comparative embodiment shown in
FIG. 13, the variable geometry turbocharger 100 (100A) shown in
FIG. 2, and the variable geometry turbocharger 100 (100B) shown in
FIG. 5.
[0056] FIG. 7 is a schematic enlarged cross-sectional view of a
variable geometry turbocharger 100 (100C) according to an
embodiment.
[0057] FIG. 8 is a schematic perspective view showing a
configuration example of a heat shield member 60.
[0058] FIG. 9 is a schematic enlarged cross-sectional view of a
variable geometry turbocharger 100 (100D) according to an
embodiment.
[0059] FIG. 10 is a schematic enlarged cross-sectional view of a
variable geometry turbocharger 100 (100E) according to an
embodiment.
[0060] FIG. 11 is a schematic enlarged cross-sectional view of a
variable geometry turbocharger 100 (100F) according to an
embodiment.
[0061] FIG. 12 is a schematic enlarged cross-sectional view of a
variable geometry turbocharger 100 (100G) according to an
embodiment.
[0062] FIG. 13 is a schematic enlarged cross-sectional view of a
variable geometry turbocharger 200 according to a comparative
embodiment.
DETAILED DESCRIPTION
[0063] Embodiments of the present invention will now be described
in detail with reference to the accompanying drawings. It is
intended, however, that unless particularly identified, dimensions,
materials, shapes, relative positions and the like of components
described in the embodiments shall be interpreted as illustrative
only and not intended to limit the scope of the present
invention.
[0064] For instance, an expression of relative or absolute
arrangement such as "in a direction", "along a direction",
"parallel", "orthogonal", "centered", "concentric" and "coaxial"
shall not be construed as indicating only the arrangement in a
strict literal sense, but also includes a state where the
arrangement is relatively displaced by a tolerance, or by an angle
or a distance whereby it is possible to achieve the same
function.
[0065] For instance, an expression of an equal state such as "same"
"equal" and "uniform" shall not be construed as indicating only the
state in which the feature is strictly equal, but also includes a
state in which there is a tolerance or a difference that can still
achieve the same function.
[0066] Further, for instance, an expression of a shape such as a
rectangular shape or a cylindrical shape shall not be construed as
only the geometrically strict shape, but also includes a shape with
unevenness or chamfered corners within the range in which the same
effect can be achieved.
[0067] On the other hand, an expression such as "comprise",
"include", "have", "contain" and "constitute" are not intended to
be exclusive of other components.
[0068] FIG. 1 is a schematic cross-sectional view of a variable
geometry turbocharger 100 according to an embodiment of the present
invention, taken along the rotational axis O of the turbocharger
100.
[0069] The variable geometry turbocharger 100 includes a turbine
rotor 2 disposed coaxially with a non-depicted compressor, a
turbine housing 6 that houses the turbine rotor 2 and forms a
scroll flow passage 4 on the radially outer side of the turbine
rotor 2, a bearing housing 10 housing a bearing 8 supporting the
turbine rotor 2 rotatably and being coupled to the turbine housing
6, and a variable nozzle mechanism 12 disposed between the turbine
housing 6 and the bearing housing 10, for adjusting the flow of
exhaust gas from the scroll flow passage 4 to the turbine rotor
2.
[0070] Hereinafter, unless otherwise stated, the axial direction of
the turbine rotor 2 is referred to as merely "axial direction", and
the radial direction of the turbine rotor 2 is referred to as
merely "radial direction", and the circumferential direction of the
turbine rotor 2 is referred to as merely "circumferential
direction".
[0071] The variable nozzle mechanism 12 includes a plurality of
nozzle vanes 14, a nozzle mount 16, a nozzle plate 18, a plurality
of lever plates 20, a drive ring 22, and a plurality of nozzle
supports 24.
[0072] The plurality of nozzle vanes 14 are disposed at intervals
in the circumferential direction, in an exhaust gas flow passage 26
having an annular shape for introducing exhaust gas from the scroll
flow passage 4 to the turbine rotor 2.
[0073] The nozzle mount 16 is an annular plate disposed on the
radially outer side of the turbine rotor 2, and forms a flow
passage wall 28 on the side of the bearing housing 10, of the
exhaust gas flow passage 26. The nozzle mount 16 is provided with a
plurality of support holes 30 (through holes) for rotatably
supporting the respective shaft portions 15 of the plurality of
nozzle vanes 14.
[0074] The nozzle plate 18 is an annular plate disposed on the
radially outer side of the turbine rotor 2 so as to face the nozzle
mount 16, and forms a flow passage wall 32 on the opposite side to
the bearing housing 10, of the exhaust gas flow passage 26.
Further, the nozzle plate 18 forms, on the downstream side of the
flow passage wall 32, a shroud wall 34 facing the tip-side ends of
the blades of the turbine rotor 2 via a gap. The nozzle mount 16
and the nozzle plate 18 are coupled by a plurality of nozzle
supports 24.
[0075] A back plate 23 is disposed between the back face of the
turbine rotor 2 and the bearing housing 10, so that exhaust gas
flowing from the exhaust gas flow passage 26 to the turbine rotor 2
does not leak toward the back side of the nozzle mount 16 (opposite
to the exhaust gas flow passage 26) through the radially inner side
of the nozzle mount 16. The back plate 23 is in contact with the
nozzle mount 16 at one end side in the axial direction, and is in
contact with the bearing housing 10 at the other end side in the
axial direction.
[0076] In the variable nozzle mechanism 12 described above, the
drive ring 22 is rotary driven by a driving force transmitted from
a non-depicted actuator. When the drive ring 22 rotates, the lever
plates 20 being in engagement with the drive ring 22 rotate the
shaft portions 15 of the nozzle vanes 14, and as a result, the
nozzle vanes 14 rotate to change the vane angle of the nozzle vanes
14, thereby adjusting the flow of exhaust gas from the scroll flow
passage 4 to the turbine rotor 2.
[0077] In the depicted embodiment, an annular space 36 housing the
lever plate 20 and the drive ring 22 is formed between the bearing
housing 10 and the nozzle mount 16.
[0078] The bearing housing 10 includes a bearing-housing side
support portion 40 having an annular shape and supporting the
radially outer portion 38 of the nozzle mount 16 from the opposite
side to the scroll flow passage 4 in the axial direction of the
turbine rotor 2. The bearing-housing side support portion 40 is
formed on the radially outer side of the annular space 36. On the
radially outer side of the bearing-housing side support portion 40,
a seal ring 41 is disposed between the turbine housing 6 and the
bearing housing, and the seal ring 41 prevents leakage of exhaust
gas from between the bearing housing 10 and the turbine housing
6.
[0079] The turbine housing 6 includes a turbine-housing side
support portion 42 having an annular shape and supporting the
radially outer portion 38 of the nozzle mount 16 from the opposite
side to the bearing-housing side support portion 40 in the axial
direction.
[0080] The nozzle mount 16 is held between the bearing-housing side
support portion 40 and the turbine-housing side support portion 42.
In the depicted embodiment, the turbine housing 6 and the bearing
housing 10 are fastened in the axial direction by a plurality of
bolts 44 disposed at intervals in the circumferential direction,
and the nozzle mount 16 is held between the bearing-housing side
support portion 40 and the turbine-housing side support portion 42
by the axial force of the bolts 44.
[0081] FIG. 2 is a schematic enlarged cross-sectional view of a
configuration example 100 (100A) of a variable geometry
turbocharger 100 (100A). FIG. 3 is a perspective view of a bearing
housing 10 of the variable geometry turbocharger 100 (100A)
depicted in FIG. 2.
[0082] In an embodiment, as shown in FIGS. 2 and 3, the
bearing-housing side support portion 40 includes at least one
bearing-housing side recess portion 46 formed so as to be recessed
opposite to the nozzle mount 16 in the axial direction. In the
depicted embodiment, the bearing-housing side support portion 40
includes a plurality of bearing-housing side recess portions 46
disposed at intervals in the circumferential direction.
[0083] According to the above configuration, with the
bearing-housing side recess portions 46, it is possible to reduce
the contact area between the bearing-housing side support portion
40 and the radially outer portion 38 of the nozzle mount 16, and to
reduce the heat release amount from the radially outer portion 38
of the nozzle mount 16 to the bearing housing 10, through the heat
insulating effect of an air layer 39 between the bearing-housing
side recess portion 46 and the radially outer portion 38 of the
nozzle mount 16. Accordingly, it is possible to reduce heat loss
due to heat release from the radially outer portion 38 of the
nozzle mount 16 to the bearing housing 10, and improve the turbine
efficiency and the performance of the turbocharger 100.
[0084] Further, it is possible to suppress a decrease in the
exhaust gas temperature of the turbine outlet side. Thus, in a case
where a catalyst for purifying exhaust gas is disposed on the
downstream side of the turbine, it is possible to suppress
performance deterioration of the catalyst due to the temperature
decrease of the catalyst, and reduce content of impurity substances
(e.g. NOx and SOx) in the exhaust gas.
[0085] FIG. 4 is a schematic diagram showing positions of a
bearing-housing side recess portion 46 and a bolt 44 with respect
to the circumferential direction.
[0086] In an embodiment, as shown in FIG. 4, with respect to the
circumferential direction, each of the bearing-housing side recess
portions 46 is formed in an angular range Ar that does not overlap
with the center position Pv of a bolt 44 adjacent to the
bearing-housing side recess portion 46, of the plurality of bolts
44.
[0087] Accordingly, for the center position Pv and the angular
range Ar do not overlap with each other, it is possible to reduce
heat loss due to heat release from the radially outer portion 38 of
the nozzle mount 16 to the bearing housing 10 while ensuring a
fastening force between the bearing housing 10 and the turbine
housing 6 achieved by the bolts 44.
[0088] In an embodiment, as shown in FIG. 4, each of the
bearing-housing side recess portions 46 is five degrees or more
apart from the center position of the bolt 44 adjacent to the
bearing-housing side recess portion 46, of the plurality of bolts
44. That is, the angle .alpha. shown in FIG. 4 is not smaller than
five degrees.
[0089] Accordingly, it is possible to reduce heat loss due to heat
release from the radially outer portion 38 of the nozzle mount 16
to the bearing housing 10 while ensuring a strong fastening force
between the bearing housing 10 and the turbine housing 6 achieved
by the bolts 44.
[0090] FIG. 5 is a schematic enlarged cross-sectional view of a
configuration example 100 (100B) of a variable geometry
turbocharger 100.
[0091] In an embodiment, as shown in FIG. 5, the turbine-housing
side support portion 42 is disposed so as to protrude inward in the
radial direction from the bearing-housing side support portion 40
along the surface 48 of the radially outer portion 38 of the nozzle
mount 16 (surface on the side of the scroll flow passage 4). That
is, the radially inner end 54 of the turbine-housing side support
portion 42 is positioned on the inner side of the radially inner
end 59 of the bearing-housing side support portion 40 with respect
to the radial direction.
[0092] Typically, as shown in FIG. 13, to nip the nozzle mount 016
with a simple structure, the radially inner end 054 of the
turbine-housing side support portion 42 is positioned on the same
position as the radially inner end 059 of the bearing-housing side
support portion 040 with respect to the radial direction.
[0093] In contrast, in the configuration shown in FIG. 5, the
turbine-housing side support portion 42 is disposed so as to
protrude inward in the radial direction from the bearing-housing
side support portion 40 along the surface 48 of the nozzle mount
16, and thus it is possible to increase the area of the nozzle
mount 16 covered with the turbine-housing side support portion 42
compared to that in a typical structure shown in FIG. 13. Thus, it
is possible to reduce the area of a portion of the nozzle mount 16
exposed to a high-temperature exhaust gas flow from the scroll flow
passage 4 to the exhaust gas flow passage 26 (heat transfer area).
Accordingly, the heat absorption amount of the nozzle mount 16
reduces, and thus an increase in the metal temperature of the
nozzle mount 16 is suppressed. Accordingly, the temperature
difference between the nozzle mount 16 and the bearing housing 10
becomes small, and thus it is possible to reduce heat loss due to
heat release from the radially outer portion 38 of the nozzle mount
16 to the bearing housing 10, and improve the turbine efficiency
and the performance of the turbocharger 100.
[0094] Further, it is possible to suppress a decrease in the
exhaust gas temperature of the turbine outlet side. Thus, in a case
where a catalyst for purifying exhaust gas is disposed on the
downstream side of the turbine, it is possible to suppress
performance deterioration of the catalyst due to the temperature
decrease of the catalyst, and reduce content of impurity substances
(e.g. NOx and SOx) in the exhaust gas.
[0095] In an embodiment, as shown in FIG. 5, the turbine-housing
side support portion 42 includes a contact portion 50 being in
contact with the radially outer portion 38 of the nozzle mount 16
and a non-contact portion 52 formed on the inner side of the
contact portion 50 with respect to the radial direction and facing
the nozzle mount 16 via a gap g. In the depicted embodiment, the
non-contact portion 52 includes a step formed from the contact
portion 50 so as to provide the gap g between the non-contact
portion 52 and the nozzle mount 16.
[0096] With the above configuration, the turbine-housing side
support portion 42 has the non-contact portion 52 on the inner side
of the contact portion 50 with respect to the radial direction, and
thus it is possible to cover the radially outer portion 38 of the
nozzle mount 16 with the turbine-housing side support portion 42
while suppressing an increase in the contact area between the
bearing-housing side support portion 40 and the radially outer
portion 38 of the nozzle mount 16. Accordingly, it is possible to
reduce the area of a portion of the nozzle mount 16 exposed to a
high-temperature exhaust gas flow from the scroll flow passage 4 to
the exhaust gas flow passage 26 (heat transfer area), and suppress
an increase in the heat input amount to the radially outer portion
38 of the nozzle mount 16 from the turbine-housing side support
portion 42. Accordingly, it is possible to suppress an increase in
the metal temperature of the nozzle mount 16 effectively, and
reduce heat loss due to heat release from the radially outer
portion 38 of the nozzle mount 16 to the bearing housing 10
effectively.
[0097] In an embodiment, as shown in FIG. 5, an expression
0.ltoreq.(r1-r3)/(r2-r3).ltoreq.0.75 is satisfied, where r1 is the
distance between the radially inner end 54 of the turbine-housing
side support portion 42 and the rotational axis O of the turbine
rotor 2, r2 is the distance between the radially outer end 64 of
the nozzle mount 16 and the rotational axis O, and r3 is the
distance between the radially outer end of the nozzle mount and the
rotational axis. In the depicted embodiment, an expression
0.ltoreq.(r1-r3)/(r2-r3).ltoreq.0.30 is satisfied.
[0098] With the above configuration, it is possible to suppress an
increase in the metal temperature of the nozzle mount 16
effectively, and reduce heat loss due to heat release from the
radially outer portion 38 of the nozzle mount 16 to the bearing
housing 10 effectively, without interfering a smooth flow in the
exhaust gas flow passage 26 between the nozzle mount 16 and the
nozzle plate 18.
[0099] Further, the bearing housing 10 in the embodiment depicted
in FIG. 5 has the same configuration as the bearing housing 10 in
the embodiment depicted in FIGS. 2 and 3, and thus the same
reference numerals are used to avoid repeating the same
description.
[0100] FIG. 6 is a diagram showing a relationship between a
temporal change of the temperature of exhaust gas flowing through
the scroll flow passage 4 (004) and a temporal change of the heat
release amount (passage heat amount) from the radially outer
portion 38 (038) of the nozzle mount (016) to the bearing-housing
side support portion 40 (040), for each of the variable geometry
turbocharger 200 according to a comparative embodiment shown in
FIG. 13, the variable geometry turbocharger 100 (100A) shown in
FIG. 2, and the variable geometry turbocharger 100 (100B) shown in
FIG. 5. In FIG. 6, the solid line indicates the temporal change of
the exhaust gas temperature that is common in the respective
embodiments, while the dotted line indicates the temporal change of
the heat release amount in the variable geometry turbocharger 200
according to a comparative embodiment. Further, the single-dotted
chain line indicates the temporal change of the heat release amount
in the variable geometry turbocharger 100 (100A), while the
double-dotted chain line indicates the temporal change of the heat
release amount in the variable geometry turbocharger 100
(100B).
[0101] As shown in FIG. 6, with the variable geometry turbocharger
100 (100A) depicted in FIG. 2, it is possible to reduce the heat
release amount (heat passage amount) from the radially outer
portion 38 (038) of the nozzle mount (016) to the bearing-housing
side support portion 40 (040), compared to the variable geometry
turbocharger 200 according to the comparative embodiment. According
to estimation of the present inventors, with the variable geometry
turbocharger 100 (100A), it is possible to reduce heat loss by
approximately 47% compared to the variable geometry turbocharger
200.
[0102] Furthermore, as shown in FIG. 6, with the variable geometry
turbocharger 100 (100B) depicted in FIG. 5, it is possible to
reduce the heat release amount (heat passage amount) from the
radially outer portion 38 (038) of the nozzle mount (016) to the
bearing-housing side support portion 40 (040), compared to the
variable geometry turbocharger 200 according to the comparative
embodiment. According to estimation of the present inventors, with
the variable geometry turbocharger 100 (100B), it is possible to
reduce heat loss by approximately 57% compared to the variable
geometry turbocharger 200.
[0103] FIG. 7 is a schematic enlarged cross-sectional view of a
configuration example 100 (100C) of the variable geometry
turbocharger 100.
[0104] In an embodiment, as shown in FIG. 7, a heat shield member
60 is disposed between the bearing-housing side support portion 40
and the nozzle mount 16.
[0105] With the above configuration, through the heat shield effect
of the heat shield member 60, it is possible to reduce the heat
release amount from the radially outer portion 38 of the nozzle
mount 16 to the bearing housing 10. Accordingly, it is possible to
reduce heat loss due to heat release from the radially outer
portion 38 of the nozzle mount 16 to the bearing housing 10, and
improve the turbine efficiency and the performance of the
turbocharger 100. Further, it is possible to suppress a decrease in
the exhaust gas temperature of the turbine outlet side. Thus, in a
case where a catalyst for purifying exhaust gas is disposed on the
downstream side of the turbine, it is possible to suppress
performance deterioration of the catalyst due to the temperature
decrease of the catalyst, and reduce content of impurity substances
(e.g. NOx and SOx) in the exhaust gas.
[0106] In an embodiment, in the variable geometry turbocharger 100
(100C) depicted in FIG. 7, the thermal conductivity of the heat
shield member 60 is smaller than each of the thermal conductivity
of the bearing housing 10 and the thermal conductivity of the
nozzle mount 16.
[0107] With the above configuration, it is possible to reduce the
heat release amount from the radially outer portion 38 of the
nozzle mount 16 to the bearing housing 10 effectively.
[0108] In an embodiment, in the variable geometry turbocharger 100
(100C) depicted in FIG. 7, the heat shield member 60 is formed of
austenitic stainless steel or nickel-based alloy. It is preferable
to use an austenitic stainless steel other than SUS 304, for
example, Cr-10Ni-6Mn-1Mo for boiler tubes. As a nickel-based alloy,
the following can be used suitably: Incoloy 800
(Ni-45Fe-21Cr-0.4Ti), Inconel 600 (Ni-16Cr-6Fe), Inconel X-750
(Ni-15Cr-7Fe-2.5Ti-0.6Al-0.8Nb), Hastelloy C (Ni-16Mo-15Cr-4W-5Fe),
or Nimonic 90 (Ni-20Cr-17Co-2.4Ti-1.4Al). Further, the heat shield
member 60 may be formed of 25Cr-20Ni anti-heat cast steel
(equivalent to SUS 310) and 35Ni-15Cr anti-heat cast steel
(equivalent to SUS 330). It should be noted that Incoloy, Inconel,
Hastelloy, and Nimonic are trademarks.
[0109] With the above configuration, it is possible to reduce the
heat release amount from the radially outer portion 38 of the
nozzle mount 16 to the bearing housing 10 effectively, while
ensuring the heat resistance performance of the heat shield member
60 itself.
[0110] In an embodiment, in the variable geometry turbocharger 100
(100C) depicted in FIG. 7, the heat shield member 60 may be a
ring-shaped heat shield plate (see FIG. 8) disposed so that the
bearing-housing side support portion 40 and the nozzle mount 16 do
not make contact with each other over the entire angular range in
the circumferential direction.
[0111] With the above configuration, it is possible to reduce the
heat release amount from the radially outer portion 38 of the
nozzle mount 16 to the bearing housing 10 through a simple
configuration.
[0112] In an embodiment, in the variable geometry turbocharger 100
(100C) depicted in FIG. 7, the heat shield member 60 may be a
coating applied to the radially outer portion 38 of the nozzle
mount 16 or the bearing housing 10 so that the bearing-housing side
support portion 40 and the nozzle mount 16 do not make contact with
each other over the entire angular range in the circumferential
direction.
[0113] With the above configuration, it is possible to reduce the
heat release amount from the radially outer portion 38 of the
nozzle mount 16 to the bearing housing 10 through a simple
configuration.
[0114] Embodiments of the present invention were described in
detail above, but the present invention is not limited thereto, and
various amendments and modifications may be implemented.
[0115] For instance, in the variable geometry turbocharger 100
(100A) described with reference to FIGS. 2 to 4, the
bearing-housing side support portion 40 includes a bearing-housing
side recess portion 46 formed so as to be recessed opposite to the
nozzle mount 16. Nevertheless, the present invention is not limited
to the above embodiment, and as depicted in FIG. 9 for instance,
the radially outer portion 38 of the nozzle mount 16 may include at
least one nozzle-mount side recess portion 62 formed so as to be
recessed opposite to the bearing housing 10 in the axial
direction.
[0116] Also with the above configuration, with the nozzle-mount
side recess portions 62, it is possible to reduce the contact area
between the bearing-housing side support portion 40 and the
radially outer portion 38 of the nozzle mount 16, and to reduce the
heat release amount from the radially outer portion 38 of the
nozzle mount 16 to the bearing housing 10, through the heat
insulating effect of the air layer 39 between the nozzle-mount side
recess portion 62 and the bearing-housing side support portion 40.
Accordingly, it is possible to reduce heat loss due to heat release
from the radially outer portion 38 of the nozzle mount 16 to the
bearing housing 10, and improve the turbine efficiency and the
performance of the turbocharger 100. Furthermore, the preferable
arrangement of the nozzle-mount side recess portion 62 in the
circumferential direction is similar to the preferable arrangement
of the bearing-housing side recess portion 46 in the
circumferential direction described above with reference to FIGS. 3
and 4.
[0117] Further, in the embodiment shown in FIGS. 2 and 3, the
bearing-housing side recess portion 46 is formed from the radially
inner side to the radially outer side of the bearing-housing side
support portion 40. Nevertheless, the formation range of the
bearing-housing side recess portion 46 in the radial direction is
not limited this. For instance, the bearing-housing side recess
portion 46 may be formed only on the radially inner side of the
bearing-housing side support portion 40 as depicted in FIG. 10,
only on the radially outer side of the bearing-housing side support
portion 40 as depicted in FIG. 11, or only in the center of the
bearing-housing side support portion 40 with respect to the radial
direction. Furthermore, also in the embodiment shown in FIGS. 10 to
12, the preferable arrangement of the bearing-housing side recess
portion 46 in the circumferential direction is similar to the
preferable arrangement of the bearing-housing side recess portion
46 described above with reference to FIGS. 3 and 4. Further, the
respective embodiments depicted in FIGS. 9 to 12 can be applied to
the respective embodiments described with reference to FIGS. 1 to
8.
DESCRIPTION OF REFERENCE NUMERALS
[0118] 2 Turbine rotor [0119] 4 Scroll flow passage [0120] 6
Turbine housing [0121] 8 Bearing [0122] 10 Bearing housing [0123]
12 Variable nozzle mechanism [0124] 14 Nozzle vane [0125] 15 Shaft
portion [0126] 16 Nozzle mount [0127] 18 Nozzle plate [0128] 20
Lever plate [0129] 22 Drive ring [0130] 23 Back plate [0131] 24
Nozzle support [0132] 26 Exhaust gas flow passage [0133] 28 Flow
passage wall [0134] 30 Support hole [0135] 32 Flow passage wall
[0136] 34 Shroud wall [0137] 36 Annular space [0138] 38 Radially
outer portion [0139] 39 Air layer [0140] 40 Bearing-housing side
support portion [0141] 41 Seal ring [0142] 42 Turbine-housing side
support portion [0143] 44 Bolt [0144] 46 Bearing-housing side
recess portion [0145] 48 Surface [0146] 50 Contact portion [0147]
52 Non-contact portion [0148] 54 Radially inner end [0149] 59
Radially inner end [0150] 60 Heat shield member [0151] 62
Nozzle-mount side recess portion [0152] 64 Radially outer end
[0153] 100 (100A to 199G) Variable geometry turbocharger [0154] 200
Variable geometry turbocharger [0155] Ar Angular range [0156] H
Arrow [0157] O Rotational axis [0158] Pv Center position [0159] g
Gap
* * * * *